Ethics seems to be the big reason. Here you are getting hit by an unwanted ad over hardware you pay for. Adbockers are an attack on hardware and IP you are us

Ethics seems to be the big reason. Here you are getting hit by an unwanted ad over hardware you pay for. Adbockers are an attack on hardware and IP you are using that someone else owns and pays for. CNN content and servers are 'free' on the condition you view their ads. You are going to them, they aren't pushing on to you.